Thanks for the reply. The article below from the IRS website makes it sound like itemizers can't, but I guess they're trying to say it's designed to benefit standard deducters, without saying that itemizers can't. A little misleading.
https://www.irs.gov/newsroom/special-300-tax-deduction-helps-most-people-give-to-charity-this-year-e...
"The Coronavirus Aid, Relief and Economic Security (CARES) Act, enacted last spring, includes several temporary tax changes helping charities, including the special $300 deduction designed especially for people who choose to take the standard deduction, rather than itemizing their deductions."
I did find another article that says it doesn't matter, but they don't cite the authoritative guidance.
https://www.kiplinger.com/taxes/tax-deductions/601279/do-you-qualify-for-a-300-tax-deduction-under-t...
"Taxpayers can take this universal deduction no matter whether they itemize or take the standard deduction on their taxes."
